EPR study of long-range acetyl-proton couplings in aliphatic acetoxy radicals

摘要: Abstract Recent liquid-phase EPR studies in our laboratory on a-formyloxy and β-formyloxy radicals, ·C(X1)(X2)OCHO [1], ·C(X1)(X2)C(X3)(X4)OCHO [2], respectively, where an (X-) group is H- or a simple substituent such as CH3−, have demonstrated that the experimentally observed long-range γ- δ-CH formyl-proton couplings were sensitive probes of alterations preferred radical conformation produced by changes degree substitution. We would expect δ- e-CH acetyl-proton acetyl-substituted a-acetoxy ·C-(X1)(X2)OC(O)CH(X3)(X4) [3], β-acetoxy ©(X1)(X2)-C(X3)(X4)OC(O)CH3 [4], to show variation with substitution similar found for structurally analogous type-[1] −[2] radicals. In present paper, we carried out comprehensive study type [3] -[4] radicals aqueous solution at approximately 25°C, particular attention couplings. Our findings successfully confirm expectations about dependence nature substituents type-[3] Furthermore, comparing variations -[3] type-[2] assigned conformations